The photosensitive composition, element, and process of this invention appear to be classifiable in one of the following classes: 430/271 or 430/306.
The art, represented by the following publications, appears to have been indifferent to the addition of selected pigments to photosensitive compositions in such a manner as to achieve a neutral black image after exposure to actinic radiation.
U.S. Pat. No. 4,335,197 discloses a method for producing a photopolymer image on a substrate which comprises exposing to actinic radiation a photosensitive layer containing dispersed silver halide in operative association with a multifunctional polymeric coupler, developing the latent image with a monofunctional developing agent, and removing the undeveloped, soluble portion by washing with aqueous solvent. U.S. Pat. No. 4,211,561 discloses a method for producing a photopolymer image employing a multifunctional developing agent in place of the monofunctional developer of the '197 patent.
U.S. Pat. No. 2,310,943 describes the use of a polyvinyl acetal carrying phenolic color-former groups, dispersed in a gelatin/silver halide photographic emulsion. Exposure to light followed by development with a color-forming developer gave a colored image. The patent also discloses use of acetal interchange to obtain a polyvinyl acetal carrying phenolic color-former groups and carboxylic acid groups.
U.S. Pat. Nos. 2,397,864 and 2,397,865 disclose acetals and related hydrophilic polymeric color-formers as the sole film-forming carrier for silver halide in a color film. The polymeric color-former is insoluble in water at 30.degree. C., and development is carried out with a conventional color-forming developer.
Procedures are known whereby exposed gelatin/silver halide layers are developed under conditions that cause tanning of the gelatin in the exposed areas. Such procedures have been used to prepare gelatin relief images in the imbibition printing of color pictures, e.g., Tull, J. Photog. Sci., 24, 158 to 167 (1976).
U.S. Pat. No. 3,904,418 discloses the use of a polymerized monomer containing at least one active methylene group as a component of a binding agent, useful in a photographic element adapted for silver-dye bleach processes.
U.S. Pat. No. 4,137,080 discloses a process for preparing color pictures by means of light-sensitive, photographic, silver halide reproducing materials in which development occurs with a polyfunctional developing agent in the presence of a polyfunctional coupler.
For a discussion of additive and subtractive color processes, see "The Theory of the Photographic Process", Fourth Edition, edited by James, Macmillan Publishing Co., Inc., New York, 1977, pages 335 to 337 including FIG. 12.1 showing Maxwell's arrangement and FIG. 12.2 showing superimposed dyes. CL SUMMARY OF THE INVENTION
This invention concerns an improved photosensitive element for photoimaging applications comprising a substrate coated with a photosensitive layer containing dispersed silver halide particles in operative association with a continuous film-forming phase of polymeric coupler, the coupler characterized by a number average molecular weight of about 2,000 to 100,000, a content of about 10 to 100 milliequivalents of coupler groups per 100 g of polymeric coupler and about 15 to 175 milliequivalents per 100 g of polymeric coupler of at least one acid group selected from carboxylic, sulfonic, and phosphonic, and the ability to couple with an oxidized p-aminodialkylaniline to become insoluble in aqueous solvents; wherein the improvement comprises said photosensitive element having dispersed therein one or more pigments of selected colors and concentrations to effect, upon photosensitization, a neutral black image characterized by an optical density imbalance of no more than about 0.5 and an optical density of at least about 2.0.
It is preferred that the optical density imbalance be no more than about 0.35. The image optical density is the sum of these optical densities: one, the coupled color coupler; two, the developed silver and; three, the added compensating pigments. Optical density measurements are made employing a conventional densitometer and standard neutral, green, blue and red filters.
This invention also concerns the photosensitive layer as a composition of matter comprising the silver halide particles, coupler and pigments described above.
The term "neutral black image" means that the (black) image has an optical density (O.D.) imbalance of no more than about 0.5 and an optical density of at least about 2.0. The term "optical density imbalance" refers to the degree of variation in optical density from neutral black toward red or green or blue. The optical density imbalance is computed as described in the last column of Table 1. Table 1 also summarizes the relationships in effect for each color of insolubilized coupler.
TABLE 1.sup.1 ______________________________________ Insolu- bilized Principal AgX Coupler Compensating Sensi- O.D. O.D. Color Pigment tized Difference Imbalance ______________________________________ Magenta Green Green A(G) - A(B) [A(G) - A(B)]/A(B) Cyan Red Red A(R) - A(G) [A(R) - A(G)]/A(G) Yellow Blue Blue A(B) - A(R) [A(B) - A(R)]/A(R) ______________________________________ .sup.1 A(G) = optical density green; A(B) = optical density blue; A(R) = optical density red.
The compositions of this invention are characterized in that relatively high photospeeds are obtained during imaging, even with relatively high pigment loading. This is accomplished because the silver halide employed is sensitized to absorb radiation in the wave length region corresponding to that where the principal compensating pigment transmits radiation.
It is preferred that the coupler comprise 30 to 80 meq per 100 g of polymeric coupler of coupler groups, and 20 to 165 meq per 100 g of polymeric coupler of carboxylic acid groups. Preferred couplers contain pyrazolone coupling groups and are between 5,000 and 60,000 in molecular weight. The preferred developer is 4-amino-3-methyl-N-ethyl-N-(.beta.-hydroxyethyl)aniline sulfate.
This invention also concerns an improvement in a method for forming a polymer photoimage comprising
(i) exposing, imagewise, a photosensitive element to actinic radiation, the element comprising a substrate coated with a photosensitive layer containing dispersed silver halide particles in operative association with a continuous film-forming phase of polymeric coupler, the coupler characterized by a number average molecular weight of about 2,000 to 100,000, a content of about 10 to 100 milliequivalents of coupler groups per 100 g of polymeric coupler and about 15 to 175 milliequivalents per 100 g of polymeric coupler of at least one acid group selected from carboxylic, sulfonic, and phosphonic, and the ability to couple with an oxidized p-aminodialkylaniline and become insoluble in aqueous solvents:
(ii) developing the layer containing the latent image with a developing agent capable of selectively reducing the silver halide in the latent image area and, in its oxidized state, of coupling with the polymeric coupler in the latent image area, thereby insolubilizing the coupler in the form of an image; and
(iii) removing the undeveloped, soluble areas of the polymeric coupler by washing with aqueous solvent;
the improvement which comprises dispersing in the photosensitive layer, before exposure to actinic radiation, pigment particles of the colors and concentrations necessary to effect, after exposure, a neutral black image.
The invention also concerns a method for forming a laminated paper proof comprising transferring the neutral black image made as described above onto a paper substrate. The invention also concerns a laminated paper proof comprising the composition of this invention characterized by a neutral black image on a paper substrate.